Pilots and other aircrew members are normally provided with a breathing mask, commonly called an oxygen mask, which is mounted on a protective helmet. The breathing mask is supplied with a pressurized supply of breathing gas, carried by the aircraft, through a supply tube. This arrangement enables the aircrew to function at altitudes where the ambient atmosphere is too "thin" to provide an adequate supply of oxygen to permit human functioning.
The supply tube usually has a coupling for attachment to an aircraft supply port. This coupling is automatically disconnected upon ejection of the aircrew during an aircraft emergency. Thus the aircrew member is ejected with a length of supply hose dangling from the mask.
If the ejection results in descent into a body of water, it is conventional for the aircrewman to remove the mask to prevent submersion of the dangling tube end into the water, thus enabling breathing of the ambient air or atmosphere. If the person is unconscious, injured or otherwise unable to manually release the mask, drowning will ensue due to oxygen deprivation or water inhalation.
It is thus necessary to automatically remove the mask to prevent drowning of an unconscious person wearing the mask.
U.S. Pat. Nos. 4,803,980 and 4,869,245 to Nowakowski et al both disclose explosive devices for disconnecting a mask from a helmet in response to an electrical signal generated by immersion of a detector in water. Arrangements of this type prevent drowning of the mask wearer due to immersion of the supply tube in water and are adequate for that purpose.
However, there are certain circumstances where a mask release is inadequate to provide breathing access for the mask wearer and prevent drowning. In one application, the mask is attached to a chemical defense hood that is worn by the aircrewman beneath the helmet and is attached to the helmet. In this instance, any release of the mask from the helmet does not remove the mask from the wearer, since it remains attached to the hood that is trapped beneath the helmet.
It is therefore desirable to provide a device which automatically provides breathing access to ambient atmosphere for the wearer of a helmet-mounted breathing mask while leaving the mask attached to the helmet.